1. Field of the Invention
The present invention relates to a sheet conveying device that conveys sheets, an image reading device, and an image forming apparatus.
2. Description of the Related Art
Japanese Patent Application Laid-open No. H10-109773 describes a sheet conveying device that conveys, using a pick-up roller, a plurality of sheets of a sheet bundle, such as a document bundle or a recording sheet bundle, stacked on a placing table to a separation nip forming a contact portion of a feed roller and a reverse roller, then separates the sheets into each single sheet using the feed roller and the reverse roller, and conveys the sheet into an apparatus.
FIG. 20 is a schematic configuration diagram of a sheet conveying device 300 described in Japanese Patent Application Laid-open No. H10-109773, and FIG. 21 is a plan view of the sheet conveying device 300 described in Japanese Patent Application Laid-open No. H10-109773.
As illustrated in FIG. 21, the sheet conveying device 300 is disposed in a cutout space 321 of a housing 320 on a body of the apparatus. A pick-up roller 322 is fixed to a pick-up shaft 326 supported as a cantilever by a pick-up swing bracket 325. A feed roller 323 is fixed to a feed shaft 327 supported as a cantilever by the apparatus body. As illustrated in FIG. 20, a reverse roller 324 is supported in the apparatus body, and is in contact with the feed roller 323 to form the separation nip.
The sheet conveying device 300 is also provided with a cover member 302 covering the pick-up roller 322 and the feed roller 323. The cover member 302 is supported, on one end side in the pick-up shaft direction thereof, as a cantilever by free ends (on the left side of FIG. 21) of the pick-up shaft 326 and the feed shaft 327.
As illustrated in FIG. 20, the cover member 302 includes an arc-shaped portion 303 that almost fully covers a side toward a placing table 330 of the outer circumference of the pick-up roller 322.
The conventional sheet conveying device 300 illustrated in FIGS. 20 and 21 has the configuration in which the cover member 302 is supported as a cantilever, and thus, the own weight of the cover member 302 or an error in mounting of the cover member 302 to the pick-up shaft 326 and the feed shaft 327 can cause the free end side (right side of FIG. 21) of the cover member 302 to come in contact with the uppermost sheet of the sheet bundle on the placing table 330. As a result, during the conveyance of sheets, the uppermost sheet of the sheet bundle on the placing table 330 can brush against the cover member 302 to be damaged. Also, an increase in conveying load of the sheet on the side of the cover member 302 can cause a conveyance trouble or a skew to occur.
Therefore, to prevent the free end side (right side of FIG. 21) of the cover member 302 from coming in contact with the uppermost sheet of the sheet bundle on the placing table 330 even when the mounting error exists, it is conceivable to set the cover member 302 and the placing table 330 to have a large clearance therebetween. In this case, however, the following problem occurs. Specifically, in a configuration in which the placing table 330 is exposed out of the apparatus, a user may temporarily place an object, such as a necklace or a ruler, other than the sheet (hereinafter called a foreign object) on top of the sheet bundle on the placing table 330. If the user starts the conveyance of sheets without remembering having placed the foreign object on top of the sheet bundle, the foreign object on top of the sheet bundle is conveyed into the apparatus together with the uppermost sheet. At this time, if the clearance between the cover member 302 and the placing table 330 is large, the cover member 302 cannot block the foreign object having a small height like the necklace or the ruler, and thus, the foreign object is conveyed into the apparatus. The problem, thus, is that the foreign object conveyed into the apparatus can damage or break the pick-up roller 322 and/or other parts.
Therefore, it is desirable to provide a sheet conveying device, a document feeder, and an image forming apparatus in which a cover member can keep foreign objects other than a sheet on a placing table from entering the apparatus so as to keep parts in the apparatus from being broken, while keeping from coming in contact with the sheet.